The present invention relates to processes for making graham-based flours which exhibit low rancidity and extended shelf-life and to baked goods having a crunchy texture made from such flours. The present invention also relates to reduced fat, low fat, or no-fat baked goods, such as graham crackers and snacks, produced from such flours.
Whole cereal grains and graham flour provide a high dietary fiber content but also provide natural lipids and enzymes, such as lipase and lipoxygenase (LPO), which may deleteriously interact during storage. The interaction of the lipids and enzymes can lead to rancidity problems such as off-flavors and odors in baked goods made from graham flour. Generally, to avoid rancidity problems in baked goods, graham flour is employed which is less than about ten days old.
Rancidity in cereal products may be due to hydrolytic (enzymatic) or oxidative degradation reactions, or both. Often, hydrolysis may predispose products to subsequent oxidative rancidity. Nature has provided a number of protective features in seeds to prevent rancidity and spoilage, enabling seeds to survive periods of adverse conditions before attaining an appropriate environment for germination and growth. Rancidity is less likely to develop when lipid materials, for example, seed oil, are unable to interact with reactants or catalysts such as air and enzymes. One protective feature in cereal grains is the provision of separate compartments for storing lipids and enzymes so that they cannot interact.
Milling cereal grains involves breaking down the separate compartments, bran, germ and endosperm, such that the lipid and enzymatic components of the grain are able to interact, greatly increasing the development of rancidity.
One problem with high-extraction flours, that is, those containing substantial amounts of bran and germ, is that they are less stable than white flours. Prolonged storage of high-extraction flours often leads to the development of rancidity. Rancidity includes adverse quality factors arising directly or indirectly from reactions with endogenous lipids, producing a reduction in baking quality of the flour, undesirable tastes and odors, or unacceptable functional properties. A main reason for the development of rancidity in high-extraction flours is the enzymatic degradation of unstable natural oils. Rich supplies of unstable natural oils are contained in the germ portion of grains used to make high-extraction flours. White flours, on the other hand, contain little or no unstable natural oils or fats because they are made from the endosperm portion of grains and are generally substantially free of bran and germ.
Another reason rancidity is a greater problem in products derived from bran and germ-containing flour is that bran and germ contain the enzymes involved in enzyme-catalyzed lipid degradation. One of the enzymes, lipase, causes hydrolytic rancidity in milling products of sound, ungerminated wheat. Lipase is found almost exclusively in the bran component. The other key lipid degrading enzyme, lipoxygenase (LPO), is present almost exclusively in the germ and also is involved in the development of rancidity. Thus, bran-containing flours or graham flours are much more susceptible to the development of rancidity than are white flours which contain little or no bran and germ.
Enzyme catalyzed lipid degradation that occurs in high extraction flour, causing rancidity in such flour, is believed to occur by the action of lipase followed by the action of LPO. When lipase, the enzyme found almost exclusively in the bran portion of the grain, is activated during milling, it reacts with unstable oils naturally occurring in the grain and breaks down the unstable oils to free fatty acids (FFA). This process may take weeks or even months. Then, LPO, the enzyme found almost exclusively in the germ portion of the grain, oxidizes FFA in the presence of oxygen producing volatile breakdown products such as peroxides that, in turn generate rancid aldehydes. In the absence of moisture, oxidation of FFA is also a very slow process and can take up to several weeks until noticeable amounts of rancid aldehydes can be detected. However in the presence of moisture, or water, which is normally added to flour in large amounts during the dough work-up stage, enzyme catalyzed oxidation of free fatty acids tends to proceed to a great extent very quickly causing formation of large amounts of rancid aldehydes in a matter of just a few minutes.
While steam and other heat sources may be used to inactivate enzymes, none have been employed in a manner to provide shelf-stable whole wheat berries and graham flour containing a low degree of gelatinized starch. Heat treatment of whole wheat berries using steam may be employed to inactivate enzymes such as lipase and LPO to provide shelf-stable flours upon milling and/or processing. However, steam heat treatment tends to substantially gelatinize starch in the berries or fails to substantially completely inactivate lipase and LPO. In Bookwalter, U.S. Pat. No. 4,737,371, for example, steam treatment for a 4-12 minute period of time only xe2x80x9csignificantly reducesxe2x80x9d lipase activity but does not substantially inactivate lipase. When steam treating under conditions sufficient to substantially inactivate lipase and LPO, steam penetrates the berries and gelatinizes a substantial amount of starch in the interior endosperm of the berries. The moisture from steam induces gelatinization of starch in the berries, when combined with the heat brought to the interior of the berries by the steam. The excessive moisture which penetrates the berries during steaming also necessitates long drying periods to reduce the moisture content to an acceptable level for milling.
Dough containing highly gelatinized starch contents that result from steam treatments to inactivate enzymes, for example more than 20% of gelatinized starch, tends to be poorly machinable and require additives to improve processing. Additives including sugar are often added to improve the machinability of highly gelatinized graham flour. However, sufficient amounts of sugar needed to improve machinability are generally inappropriate for low-calorie applications, such as reduced fat, low-fat and no-fat crackers.
Whole wheat berries and graham flours having higher degrees of gelatinized starch may be acceptable for applications wherein crunchy baked products are desired. It has been found by the present inventors that crackers made from whole wheat flour having from about 5% to about 20% gelatinized starch obtained using infra-red heating are unexpectedly crunchier than crackers made from whole wheat flour having ungelatinized starch. Likewise, baked goods made from dough containing less than about 5% of gelatinized starch are not as crunchy as baked goods made from dough comprising flours having from about 5% to about 20% gelatinized starch. However, dough containing flour having more than 20% of gelatinized starch, e.g. more than about 25% gelatinized starch, tends to be too short, or not very elastic, and is thus poorly machinable because it tends to break and tear when sheeted.
Another problem encountered with unstable wheat flour is that wax paper packaging or other semipermeable packaging must be used to permit the escape of rancid odors from such products. Metallized film packaging has been avoided for such applications as they do not permit the escape of rancid odors which often accompany unstable whole wheat flour and products. Metallized film packaging is desirable, however, in the snack food industry because of its ability to preserve the freshness of a packaged product and to prevent the product from absorbing moisture and odors. Aesthetics requirements have also led to an increased use of metallized film packaging. Stable flours and baked goods that have long shelf-lives, for example, 45 days or longer, do not require semipermeable packaging because they do not produce sufficient amounts of rancid odor to require continuous release thereof from the packaging. Stable flours and baked goods can thus be packaged in non-permeable packaging. Unstable flours, including whole wheat and graham flours, and products, however, cannot be packaged in non-permeable materials. Therefore, it is desirable to provide shelf-stable graham or whole wheat flour and baked goods which can be packaged in metallized film packaging materials without a need to provide for an escape of rancid odors.
To avoid the excess gelatinization and moisture content in the interior of whole wheat berries that is caused by steam treating the berries to stabilize them, it is desirable to select a substantially steam-free form of enzyme-inactivating energy to treat the berries. Lipase is concentrated in the bran of whole wheat berries, and LPO in the germ. Accordingly, it is also desirable to focus enzyme-inactivating energy at the exterior portions of whole wheat berries where the bran and germ are located. Localizing the energy applied to the exterior parts of the berries enables substantial or complete inactivation of lipase and LPO in the entire berries without substantially treating the interiors of the berries where starch is prevalent. Thus, by concentrating an irradiative energy source, for example infrared (IR) radiation, in a controlled fashion on the exterior of the berries, heating and gelatinization of starch in the endosperm portions of the berries are minimized.
The present invention is based on the need for shelf-stable whole wheat berries and graham flour having a low degree of gelatinized starch. The present invention provides a process for making shelf-stable whole wheat berries and graham flour having a low degree of gelatinized starch and which yield a crunchy texture in baked goods. The present invention also provides a process for making reduced fat, low-fat or no-fat graham-based crackers which have a crunchy texture and a long shelf-life.
The present invention provides a process for inactivating enzymes in whole wheat berries which cause degradation of natural lipids in milled whole cereal grains. A controlled, localized application of lipase and LPO inactivating energy at the surface of the berries provides a degree of starch gelatinization which does not adversely affect dough machinability, without the need for additives. The graham flours produced according to the invention possess a stable shelf life which exceeds 45 days. A crunchy texture is unexpectedly exhibited in baked goods baked from the stabilized graham flour. Also, the present invention delivers consistent functionality to baked products and allows the use of metallized packaging films without detrimental effects.
The present invention also provides a method of whole wheat berry stabilization which meets the standard of identity for ingredient labeling identifying the wheat component as xe2x80x9cwhole wheatxe2x80x9d. Whole wheat that is stabilized by removing the bran, stabilizing it, and then recombining with the unstabilized wheat components cannot be considered or labeled xe2x80x9cwhole wheatxe2x80x9d since the supplier cannot guarantee that the proportion of the components after recombining are consistent with the proportions in whole wheat before stabilization. According to the present invention, whole wheat berries are treated and products incorporating flour made from such berries can properly be labeled xe2x80x9cwhole wheat.xe2x80x9d
The present invention relates to a process for making shelf-stable graham flour which yields a crunchy texture in baked goods, wherein the flour is made from whole wheat berries treated under conditions that inactivate lipase and lipoxygenase (LPO) yet gelatinize less than about 20% of the starch in the berries. The present invention relates to a process for making reduced fat, low fat or no fat baked goods such as graham crackers or snacks which have a crunchy texture and a long shelf-life.
In accordance with the present invention, a graham flour is made from whole wheat berries that have significantly reduced lipase and LPO enzyme activity. To achieve significant reduction in enzyme activity, according to the present invention, berries of a specified moisture content are irradiated by an infrared (IR) energy source until a desired berry surface temperature is achieved. The irradiated berries are then cooled, dried and comminuted. The berries may first be moisturized with water for a period of time to achieve a desired moisture level. Also, the berries may optionally be maintained at an elevated temperature for a period of time after irradiation treatment. The moisturizing conditions, amount of IR irradiation, temperatures, and periods of time for IR treatment and subsequent heat treatment are chosen to be sufficient to at least substantially inactivate lipase and LPO in the berries yet insufficient to gelatinize more than about 20% of the starch in the berries. Starch gelatinization may generally range from about 5% to about 15% as measured by differential scanning calorimetry. The graham flour obtained by the method of the present invention has an excellent shelf-life. Additionally; baked goods made from the flour have both an excellent shelf-life and a surprisingly crunchy texture.
The shelf-stable whole wheat or graham flour may be produced in accordance with the method of the present invention by:
(1) providing whole wheat berries having a moisture content of from about 15% by weight to about 20% by weight, if necessary by moistening the berries to achieve said moisture content;
(2) subjecting the moistened whole berries to a heat treatment including IR energy for a first period of time to heat the berries to a first temperature of from about 90xc2x0 C. to about 120xc2x0 C.;
(3) cooling the heated berries after said first period of time to a temperature of about 73xc2x0 C. or lower to substantially prevent further gelatinization of starch in the berries;
(4) drying the berries to a moisture content of from about 10% to about 15%; and
(5) comminuting the berries to obtain a graham flour.
After IR energy treatment and before cooling, the berries may also be held for a second period of time at an elevated temperature of from about 80xc2x0 C. to about 110xc2x0 C. The second period of time may range up to about two hours or more. The optional elevated temperature treatment can improve inactivation of enzymes in the berries, although some further gelatinization of starch usually occurs. The first and second periods of time are preselected to achieve substantial inactivation of lipase and LPO in the berries without gelatinizing more than 20% of starch in the berries. The optional elevated heat treatment can also help reduce the moisture content of the berries, thereby reducing or eliminating the need for drying the berries to reduce moisture.
Initial moistening of the berries may not be needed if the berries to be treated have a moisture content of from about 15% by weight to about 20% by weight prior to treatment. If employed, the moistening step involves moistening whole wheat berries under conditions which result in a relatively higher concentration of moisture in exterior portions of the berries than in the interior portions of the berries. In accordance with the present invention, moistening times are limited to periods of time sufficient to absorb an added amount of water, yet of insufficient length to allow substantial deep absorption of water into interior portions of the berries. The moisture gradient facilitates inactivation of lipase and LPO in the outer portions of the berry while limiting gelatinization of starch in the inner, endosperm portion of the berry.
Reduced fat, low fat, or no-fat baked goods such as graham crackers and snacks may be produced in accordance with the present invention by admixing the whole wheat or graham flour obtained by the IR enzyme inactivation process of the present invention with ingredients comprising water to form a machinable dough. The dough may be formed into pieces, and the pieces may be baked to obtain crunchy-textured baked goods.
The present invention provides an improved raw material stability and provides graham flour having a shelf life of greater than 30 days, for example 45 days or more, delivers consistent functionality to baked products, allows the use of metallized packaging films without detrimental effects upon flavor or aroma, and provides an unexpectedly crunchy-textured, shelf stable baked good. In addition, the present invention provides a method of treating whole wheat berries without the need to remove, treat and recombine portions of the berries. Therefore, the term xe2x80x9cwhole wheat berries,xe2x80x9d as it is used in the present invention, refers to berries that include all of the bran, germ and endosperm portions intact. The ingredient listings for products containing the treated berries or flours of the present invention can therefore identify the wheat as whole wheat.
The present invention relates to a process for making low rancidity shelf-stable graham flour having an unexpectedly long shelf life and which forms a machinable dough. The machinable dough is bakeable to an unexpectedly crunchy texture and provides baked goods having an extended shelf life. The present invention provides a process for inactivating lipase and lipoxygenase (LPO) in whole wheat berries, while achieving a degree of starch gelatinization in the berries of about 20% or less, preferably 15% or less, as measured by differential scanning calorimetry (DSC). The present invention also relates to a process for making reduced fat, low fat or no-fat graham-based crackers which have a crunchy texture and a long shelf-life.
Substantial inactivation of lipase and LPO is critical in accordance with the present invention because these two components are believed to be primarily responsible for enzyme catalyzed rancidity of the graham flour. However, it may be difficult to eliminate activity of both these enzymes without treating the grains and gelatinizing starches to an undesirable level. In the preferred embodiment of the present invention: a) the lipase activity is negative (as measured, for example, by an OAT-CHECK lipase enzyme activity test kit available from LAB PRODUCTS, A division of ALTECA, Inc. Kansas, USA), and b) the amount of LPO is less than about 10%, preferably less than 5% of the original amount of LPO present in untreated berries. In the most preferred embodiment, both lipase and LPO activities are completely eliminated, while the extent of gelatinization of starch in the grains remains below 20%.
Generally, starch gelatinization occurs when: a) water in a sufficient amount, generally at least about 30% by weight, based upon the weight of the starch, is added to and mixed with starch and, b) the temperature of the starch is raised to at least about 80xc2x0 C. (176xc2x0 F.), preferably 100xc2x0 C. (212xc2x0 F.) or more. The gelatinization temperature depends upon the amount of water available for interaction with the starch. The lower the amount of available water, generally, the higher the gelatinization temperature. Gelatinization may be defined as the collapse (disruption) of molecular orders within the starch granule, manifested in irreversible changes in properties such as granular swelling, native crystallite melting, loss of birefringence, and starch solubilization. The temperature of the initial stage of gelatinization and the temperature range over which it occurs are governed by starch concentration, method of observation, granule type, and heterogeneities within the granule population under observation. Pasting is the second-stage phenomenon following the first stage of gelatinization in the dissolution of starch. It involves increased granular swelling, exudation of molecular components (i.e. amylose, followed by amylopectin) from the granule, and eventually, total disruption of the granules. See Atwell et al., xe2x80x9cThe Terminology And Methodology Associated With Basic Starch Phenomena,xe2x80x9d Cereal Foods World, Vol. 33, No. 3, pgs. 306-311 (March 1988).
In accordance with the present invention, a process for making graham flour having reduced or completely eliminated lipase and LPO enzyme activity is provided wherein IR energy is used to irradiate moistened whole wheat berries for a first period of time sufficient to raise the temperature of the berries to from about 90xc2x0 C. to about 120xc2x0 C., as measured with a temperature probe inserted into and centrally positioned within the lot of the treated berries to measure their surface temperature.
In accordance with a preferred embodiment of the invention, infrared (IR) energy is used to heat the berries to a temperature of from about 95xc2x0 C. to about 115xc2x0 C., with the range of from about 100xc2x0 C. to about 110xc2x0 C. being more preferred for some applications. For example, in a preferred embodiment of the invention, berries are treated with IR energy until they reach a temperature of about 105xc2x0 C., however the temperature may vary depending on subsequent treatment of the berries. The first period of time sufficient for IR treatment to inactivate lipase and LPO ranges from 10 seconds to 2 minutes, preferably from 30 seconds to 60 seconds.
The use of IR energy is an important feature in accordance with the present invention. According to the invention, it has been determined that because lipase is concentrated in the bran of whole wheat berries, and LPO in the germ, it is desirable to focus enzyme-inactivating energy at the exterior portions of whole wheat berries where the bran and germ are located. Localizing the energy applied to the exterior parts of the berries enables substantial or complete inactivation of lipase and LPO in the entire berries without substantially irradiating the interiors of the berries where starch is prevalent. Thus, by concentrating the energy source on the exterior of the berries, heating and gelatinization of starch in the endosperm portions of the berries are minimized. IR irradiation treatment allows for controlled localized application of energy, thus enabling the achievement of the desired goal of surface treatment of berries. Subsequent heat treatment may be needed to enhance the effect of IR irradiation treatment in inactivation of lipase and LPO.
In accordance with the present invention, IR energy is supplied by a source which emits wavelengths of electromagnetic energy in the IR region, preferably in the range of from about 1.8 microns to about 3.4 microns. According to some embodiments of the invention, the source emits wavelengths of energy in the range of from about 2.2 to about 3.0 microns. Suitable devices for infrared treatment of the berries according to the methods of the present invention are IR energy treatment devices known as micronizers, available from Micronizer, Inc.
The wavelengths of electromagnetic energy used according to the invention penetrate whole wheat berries only to a shallow depth, and can be controlled so as not to substantially heat the endosperm portions of the berries. Thus, the portions of berries most affected by the irradiated energy are exterior portions, where bran and germ are located. As a result, the enzymes in the exterior portions of the berries are primarily affected and inactivated by the emitted radiation. The bran and germ absorb the major proportion of the IR radiation, thus allowing for effective treatment of lipase and LPO concentrated in the bran and germ without exposing interior portions of the berries to high amounts of energy from the source. Much higher wavelengths of energy, for example, in the 20 centimeter to 50 centimeter range, would not be useful according to the invention because such wavelengths would penetrate deeper into the berries and cause substantial gelatinization of starch in interior portions thereof. By using wavelengths of energy in the IR region, enzymes in exterior portions of the berries can be inactivated without substantially affecting or gelatinizing starch in interior portions to such an extent as would deleteriously affect dough machinability.
In accordance with the present invention, a combined IR energy and heat treatment is used to substantially inactivate lipase and LPO in moistened whole wheat berries, while gelatinizing only from about 5% to about 20% of starch in the berries, preferably from about 7% to less than about 15%, more preferably from about 8% to about 12% as determined by differential scanning calorimetry (DSC). At a lower extent of gelatinization, for example, less than about 5%, machinability is good but baked products made from the dough are not as crunchy as products made from dough of flour having about 5% to about 20% starch gelatinization. At a higher extent of starch gelatinization, for example, more than 20%, dough made from the resulting flour tend to be too short, that is, not very elastic, and is thus difficult to machine because it breaks and tears when sheeted.
Another way to determine whether berries have been overtreated or over gelatinized is to measure peroxidase enzyme activity. Peroxidase is another enzyme which is primarily found in the bran layer. Peroxidase enzyme does not participate or catalyze rancidic lipid degradation, and, therefore, its activity need not to be altered or suppressed. However, measuring of peroxidase activity can be used as an indicator of inactivation of either lipase or LPO. It also can be used as an indicator of possible overtreatment of whole wheat berries. Peroxidase enzymes are much more stable than either lipase or LPO, and their deactivation in whole wheat berries requires prolonged treatment at high temperatures. Complete inactivation of peroxidase enzyme in graham flour obtained in accordance with the present invention, therefore, would most likely indicate complete inactivation of both the lipase and LPO enzyme activities. However, complete inactivation of peroxidase would also indicate overtreatment of the berries, resulting in a high degree of gelatinization.
According to the present invention, the moisture content of the berries is also controlled to provide substantial lipase and LPO inactivation with minimal starch gelatinization. The berries may be treated or tempered such that exterior portions of the berries are moistened without substantially moistening interior portions thereof. Such treatment enhances the absorption of IR energy at exterior portions of the berries, with little penetration of IR energy to interior portions of the berries. By moistening the exterior portions, and not the interior portions of the berries, the present invention enables absorbed energy to be concentrated in exterior portions of the berries, where lipase and LPO are stored.
In accordance with the present invention, exterior portions of whole wheat berries can be moistened without substantially moistening interior portions of the berries. Tempering methods which can be used to accomplish a moistening treatment according to the invention include soaking the whole wheat berries for limited time periods in a bath or vat, for example. In other embodiments, the whole berries may be surface sprayed with water and permitted to soak or temper. Soaking or tempering times of from about 10 minutes to about 120 minutes may be employed according to some embodiments of the invention, but soaking for about 30 minutes to about 90 minutes is preferred. Soaking the berries for a longer time period is not desirable because it may result in deep penetration of water into the berries, moistening the interior portion of the berries. Berries subject to long tempering times and subsequently treated with IR energy tend to exhibit a higher amount of starch gelatinization when compared to berries tempered for shorter periods of time and irradiated to the same exterior temperature.
Tempering treatments which substantially avoid moisture penetration deep into the interiors of berries result in lower degrees of starch gelatinization when compared to deep moistening treatments. In accordance with the present invention, tempering is conducted for a long enough period of time to moisten exterior portions of berries and achieve a desired overall moisture content, but for a short enough period of time to minimize moistening of interior portions of the berries. The period of time for tempering also depends upon the desired amount of moisture to be added to the berries, with longer tempering times needed to add more moisture to the berries and shorter tempering times needed to add less moisture.
The moisture content of the berries immediately prior to IR treatment can be critical to achieving inactivation of lipase and LPO with only about 20% or less gelatinization. According to embodiments of the present invention, whole wheat berries are moistened or tempered for a period of time to achieve a moisture content of from about 15% by weight to about 20% by weight, with amounts of from about 17% by weight to about 19% by weight being preferred, for example, 18% by weight.
Natural whole wheat berries generally have a moisture content of from about 10% by weight to about 14% by weight. Accordingly, in embodiments of the invention, substantial amounts of water are added to raise the moisture content to an acceptable level for IR energy treatment. Adding from about 2% by weight to about 5% by weight water to the berries is generally preferred for moistening whole wheat berries, with added water amounts of from about 3.5% by weight to about 4% by weight being more preferable for tempering untreated whole wheat berries. Exceptionally dry untreated berries may require as much as about 9% by weight added water to achieve a moisture content of about 19% by weight, whereas exceptionally moist untreated berries may only require the addition of about 1% by weight of water, or no water at all.
In accordance with the present invention wherein a heat-treatment is used to subsequently treat the berries after exposure to IR energy, the subsequent heat treatment preferably involves maintaining the IR energy-treated berries in holding bins at a surface temperature of from about 80xc2x0 C. to about 110xc2x0 C., more preferably from about 85xc2x0 C. to about 100xc2x0 C., for a period of time of up to about one hour, or longer. Generally, the treatment time may be at least about 8 minutes. As the period of time increases, the degree of starch gelatinization generally increases. However, when the IR energy treatment does not by itself sufficiently inactivate lipase and LPO in the berries, the berries may be maintained at an elevated temperature to complete substantial inactivation of the enzymes.
Holding or residence times may vary depending upon each of the temperature at which the treated berries are maintained and the temperature achieved during the IR treatment stage. Treatments for more than about one hour may cause substantial gelatinization of starch in the berries. For embodiments wherein IR energy treatment of the berries results in a surface temperature of from about 100xc2x0 C. to about 110xc2x0 C., subsequent heat treatments at temperatures of from about 85xc2x0 C. to about 95xc2x0 C. for up to 10 minutes are preferred, more preferably from about 8 minutes to about 10 minutes. For embodiments wherein IR energy treatment of the berries results in a temperature of about 120xc2x0 C., it is preferred not to use a subsequent heat treatment but instead to immediately cool the berries after IR exposure, or to cool the berries shortly after exposure, for example, within about 20 minutes.
Cooling the berries after IR energy treatment or after IR energy and subsequent heat treatment can be controlled to further minimize undesired gelatinization of starch. According to some embodiments of the invention, rapid cooling of the heated berries is preferred, for example, with chilled or room temperature ambient air. The berries are usually cooled to a surface temperature below 73xc2x0 C. within 60 minutes. Then the berries are cooled to room temperature, or about 25xc2x0 C. A temperature of 73xc2x0 C. is a critical temperature because generally no further significant gelatinization occurs in the berries at temperatures lower than 73xc2x0 C. In embodiments wherein IR energy-treated berries are cooled immediately after IR treatment, the average cooling rate used to achieve a surface temperature of about 25xc2x0 C. is preferably a temperature decrease of from about 1xc2x0 C. per minute (1xc2x0 C./min) to about 3xc2x0 C./min over a period of up to about 30 minutes, with average cooling rates of about 2xc2x0 C./min over a period of up to about 30 minutes being more preferred. In embodiments wherein IR energy-treated berries are subsequently heat-treated and then cooled after heat-treatment, the cooling rate to achieve a surface temperature of about 25xc2x0 C. preferably averages a temperature decrease of from about 1xc2x0 C./min to about 3xc2x0 C./min, with cooling rates of about 2xc2x0 C./min being more preferred. Higher cooling rates of more than about 3xc2x0 C./min, result in a more rapid decrease in surface temperature and can be used with shorter cooling periods. Lower cooling rates of less than about 1xc2x0 C., result in a slower decrease in surface temperature, and can be employed with longer cooling periods.
The cooling rate should be selected to minimize further gelatinization of starch in the berries after IR energy treatment or after heat-treatment, but should not be so fast as to prevent further inactivation of lipase and LPO, if needed. If no further inactivation of lipase or LPO is desired, cooling should be conducted to quickly reduce the temperature of the treated berries to less than about 73xc2x0 C. For example, a higher cooling rate may be employed for initial cooling of the treated berries, followed by a lower cooling rate. Also, the cooling rate can be selected to dry the berries to various degrees. For example, longer cooling periods at lower cooling rates provide drier berries when compared to berries cooled at higher cooling rates for shorter periods of time.
A cooler or cooling device is preferably located at the exit of a bin, for example a surge bin, which receives heat-treated berries. Herein, the term xe2x80x9cheat-treatedxe2x80x9d refers to berries which have been IR energy treated, with or without a subsequent treatment at an elevated temperature. The cooler may be located, for example, adjacent the exit of a bin used as an IR energy treatment device. The cooling device may instead be arranged at the exit of a holding bin or surge bin wherein berries are held for a period of time at an elevated temperature. Whole berries may be fed to the cooler by a rotary feeder disposed at a holding bin or surge bin exit.
Coolers which may be used for the processes of the invention include cooling tubes or cooling tunnels through which berries pass under the force of gravity or on a conveyor device. While the heat-treated berries pass through the device, cooled air is passed over and through the berries. The spent cooling air may then be collected or suctioned off, for example, by a hood, and further treated in a cyclone separator. A preferred cooler supplies cooling air to various regions along the length of a cooling tube or tunnel. Preferably, the cooling air is passed through a chilling device prior to contacting the berries to achieve a temperature which is lower than that of ambient air. The cooled berries exiting the cooler can be immediately milled or bagged.
Coolers having a tubular or tunnel-like construction are preferred according to the present invention. When employed, berries having a high surface temperature are fed or otherwise directed to a cooler entrance. A surface temperature profile for the cooler can be extrapolated by measurements of surface temperature of berries along the length of the cooler. Probes positioned at various distances along the cooler can provide such temperatures.
After cooling, the moisture content of the berries may further be reduced by drying. Drying temperatures of less than about 73xc2x0 C. are preferred so that no further gelatinization of starch occurs during the drying process. In accordance with the present invention, drying temperatures range from about 0xc2x0 C. to about 73xc2x0 C. However, drying at ambient temperature is less expensive than drying at a cooler temperature and will prevent further gelatinization of the starch in the berries during drying. Drying is preferably conducted in an atmosphere having a low relative humidity, and may preferably be conducted in a reduced pressure atmosphere. In accordance with the present invention, drying may be performed until the moisture content of the berries is reduced to within the range of from about 10% by weight to about 15% by weight, preferably from about 12% by weight to about 14% by weight.
If the IR energy treatment and the optional further heat treatment achieve moisture contents within a desired range, no drying step is deemed necessary. Moisture contents of from about 10% by weight to about 15% by weight are preferred for milling purposes, to with moisture contents of about 12.5% by weight to about 13% by weight being particularly preferred. If there is too little moisture in the berries, the berries will undesirably shatter, creating a damaged starch product that is difficult to mill. Too high an amount of moisture renders the berries susceptible to excessive starch gelatinization and also causes the berries to be difficult to mill. For these reasons, dried berry moisture contents of from about 12% by weight to about 14% by weight are preferred just prior to milling.
If the moisture content in the heat-treated berries is too low, moisture may be added to the dry berries prior to milling to increase the moisture content to an acceptable level for milling. A tempering operation performed after IR energy treatment of the berries is referred to herein as xe2x80x9cpost-treatment tempering.xe2x80x9d The post-treatment tempering may be performed in a manner similar to the pre-treatment tempering. The moisture content of the treated berries can be increased by post-tempering for a period of time, for example, from about 10 minutes to about 240 minutes. According to a preferred embodiment of the invention, tempering is conducted to bring the moisture content of the berries up to from about 12% by weight to about 15% by weight. The desired increase in moisture is generally much less than the increase achieved by pre-treatment tempering. Accordingly, post-treatment tempering may be conducted for shorter periods of time than pre-treatment tempering. Post-treatment tempering generally adds from about 2% by weight to about 5% by weight of water to the whole wheat berries. The amount of water which should be added by a post-treatment tempering can be determined, based on the weight of the treated berries, as the difference between the measured moisture content and the desired moisture content. Thus, for example, if the measured moisture content of treated berries is 11.5% by weight and a moisture content of 12.5% by weight is desired, 1% by weight moisture should be added to the berries, or one pound of water should be added for every 100 pounds of treated berries.
Methods according to the present invention provide treated whole wheat berries having degrees of starch gelatinization of about 20% or less as measured by the DSC method. In addition to achieving a desired degree of gelatinization, the solvent retention capacity (SRC) of the flour from the treated berries of a desired value can be achieved according to the methods of the present invention. SRC is a physical property that determines usefulness of the berries in a subsequent baking process. SRC is an indirect measurement of the extent of starch gelatinization and it generally exhibits a direct correlation with the results obtained from the DSC measurements. SRC functionally shows how the flour will behave in baking a product. SRC values of from about 65 to 91 are acceptable values, with from about 70 to about 75 being preferred. SRC values of greater than or equal to about 91 generally correspond to degrees of gelatinization of greater than 20% and to overtreated berries, and thus are undesirable.
In accordance with the present invention, the graham flour of the invention is admixed with cracker ingredients including water to form a dough. The dough may be continuously produced and machined, for example sheeted, laminated, and cut, on a mass production basis. The dough is then formed into pieces and the pieces are baked to obtain a cracker having a crunchy texture. Baking generally inactivates any residual lipase and LPO in the flour. Accordingly, shelf-stability of the baked products is not as much of a concern as the stability of the graham flour or the raw dough.
In addition to water, cracker ingredients which may be admixed with the graham flour of the present invention include enriched wheat flour, vegetable shortening, sugar, salt, high fructose corn syrup, leavening agents, flavoring agents and coloring agents. Enriched wheat flours which may be used include wheat flours enriched with niacin, reduced iron, thiamine mononitrate and riboflavin. Vegetable shortenings which may be used include those made of partially hydrogenated soybean oil. Leavening agents which may be used include calcium phosphate and baking soda. Coloring agents which may be used include vegetable coloring agents such as annatto extract and turmeric oleoresin.
Dough made in accordance with the present invention includes dough comprising various combinations of the aforementioned cracker ingredients. According to some embodiments, all of the foregoing cracker ingredients are homogeneously admixed and the amount of water is controlled to form a cracker dough of desired consistency. The dough may then be baked to produce crackers having a crunchy texture. The baked goods produced in accordance with the present invention may be crackers or cookies having a full content or they may be a reduced fat, low-fat, or no-fat product.
As used herein, a reduced-fat food product is a product having its fat content reduced by at least 25% by weight from the standard or conventional product. A low-fat product has a fat content of less than or equal to three grams of fat per reference amount or label serving. However, for small reference amounts (that is, reference amounts of 30 grams or less or two tablespoons or less), a low-fat product has a fat content of less than or equal to 3 grams per 50 grams of product. A no-fat or zero-fat product has a fat content of less than 0.5 grams of fat per reference amount and per label serving. For accompaniment crackers, such as a saltine cracker, the reference amount is 15 grams. For crackers used as snacks and for cookies, the reference amount is 30 grams. Thus, the fat content of a low-fat cracker or cookie would therefore be less than or equal to 3 grams of fat per 50 grams or less than or equal to about 6% fat, based upon the total weight of the final product. A no-fat accompaniment cracker would have a fat content of less than 0.5 grams per 15 grams or less than about 3.33%, based upon the weight of the final product.
The present invention provides an improved raw material stability and greater than 30 day shelf life, for example 45 days or more, delivers consistent functionality to baked products, allows the use of metallized packaging films without detrimental effects, and provides an improved product quality relative to products made from similar, but untreated, whole wheat berries. In addition, the present invention provides a continuous method of treating whole wheat berries without removing, treating and recombining portions of the berries. The ingredient listings for products containing the treated berries or flours of the present invention can therefore identify the wheat as whole wheat.
The present invention is illustrated by the following non-limiting examples wherein all parts, percentages, and ratios are by weight, all temperatures are in xc2x0 C., and all temperatures are atmospheric, unless indicated to the contrary: